HIGH-ENERGY HEAVY-ION IRRADIATION EFFECTS IN ALPHA-AL2O3

Single crystals of Al2O3 have been irradiated at GANIL with 3.5 MeV/amu Pb ions, at a temperature of congruent-to 80 K. The fluence range extended from 4 X 10(11) to 1.2 x 10(12) ions cm-2. The effects of high electronic excitation induced in the samples have been characterized by Rutherford backscattering ion channeling (RBS) in conjunction with optical absorption measurements. Moreover, some samples preliminary implanted with 10(16) Fe-57+ ions cm-2 at 110 keV and annealed at 1673 K during one hour were studied using conversion electron Mossbauer spectroscopy (CEMS) in order to obtain complementary informations. Preliminary RBS results (77 K irradiations) indicate a damage cross section of approximately 10(-13) cm2, consistent with a track radius of about 1.8 nm. The defect efficiency has been also investigated as a function of the electronic stopping power (dE/dx)e.